1. Field of the Invention
The present disclosure relates to intense light shielding or blocking methods, mechanisms, devices, and systems that detect and track intense light sources within a viewer field of vision/view (FOV) and then provide localized active shades against a globally lower and adjustable background attenuation via a Liquid Crystal Display (LCD) shutter screen allowing for an improved view of the world from behind viewing glasses in a dynamic motion environment.
Conventional mechanical Sun visors are not transparent and block a large portion of the FOV, limited sun coverage over FOV thus leaving the operator susceptible to direct sun illumination resulting in temporary blindness and also much discomfort from the additional heat. Sunglasses provide uniform shading effect reducing eye saturation when looking in the direction of the sun but also reduce the visibility of overall scene. Eyeglasses, visors, goggles, head-up display glasses/combiners, vehicle windows/windshields, glass-windows/roofs, aircraft cockpit glasses and overhead canopy in fighter planes are devices and applications that inherit disadvantages of conventional mechanical visor or tinting causing reduced visibility, much viewing fatigues, discomfort, and safety related risks for their operators. Other efforts, cited in patents on related applications, involved the use of large LCD panels to provide sun shade against large portions of the field of vision or the relative sun to human detection techniques suggested were cumbersome, archaic and not feasible for practical implementations.
This invention uses digital cameras to image the view of the world from out-of-the-cockpit or behind viewing glasses. The imagery is used to control an LCD shutter screen imbedded in sunglasses or windshields for casting localized active shades against a lower attenuation globally uniform or gradient background over the entire field of view in a dynamic motion environment. The objective is to image the intense light sources and to actively generate localized shades allowing the viewer to comfortably observe his surrounding without visual saturation effects caused by direct intense illumination while preserving visual acuity and sensitivity via a lower light attenuation background.
The Active Shielding Against Intense Illumination (ASAII) system can also be implemented as Dynamic Contrast filters for enhanced contrast imaging capability in digital optical systems. In these imaging applications, the ASAII system uses the LCD shutter screen behind the lens assembly in the imaging plane for casting localized active shades over saturated picture elements (pixels) against a selectable lower background attenuation allowing for higher contrast imaging capability bright backgrounds even with the sun in direct view.
2. Description of the Related Art
Liquid Crystal Display (LCD) shutter screens are widely used for imaging with back lighting in large high definition television systems. LCD screen provides light intensity modulation via electrically-controlled high-speed switching open and close of the picture elements causing variable light attenuation during image formation. LCD switching can achieve contrast ratio greater than 10,000:1 between the highest and lowest intensity picture elements (pixels) or even much better performance as evidently achieved in Liquid Crystal light modulators (amplitude modulator with rise and fall times in the neighborhood of 200 picoseconds for light pulsing or equivalently better than 2 MHz LCD shutter speed). When imbedded in viewing glasses, the LCD screen can be used to generate and cast locally active shades against an adjustable uniform or gradient background in dynamic motion environment.
The proliferation of digital imaging capability, in devices such as the mobile cellular phones, cameras and camcorders, has made this technology perfectly suitable for intense light/sun detection and tracking in a dynamic motion environment. Wide angle imaging cameras with a relatively simple image processing algorithm and adjustable intensity thresholds can be employed to detect and actively track the sun relative to the camera boresight or its imaging direction which shall be co-linearly aligned with the confined viewing direction from out-of-the cockpit or behind personal sunglasses.
Recent advances in the development of microprocessor offer many choices and possibilities in designing a relatively powerful processor that requires low power consumption. One can readily find similar types of processor used in applications such as smart credit cards, personal identification badges, and electronic wallets. For Active Sun Shade applications, the processor requires minimum computational power to accept user alignment input data via rocker switches, to perform Shade and Camera Boresight alignments, and to control the LCD screen switching operation. A small size low power processor may employ solar power source allowing for light weight and more fashionable stylistic sunglasses designs.